Electrical delay-circuit arrangement



April 29, 1930. E. w. NILES ET AL 1,756,097

ELECTRICAL DELAY CIRCU IT ARRANGEMENT Filed Sept. 24, 1928 2 Sheets-Sheet l Minutes Daratw/z/ q/Current Flow;

9" INVENTORS Al IQRNEY April 2 9, 1930 w, MILES ET AL ELECTRICAL DELAY CIRCUIT ARRANGEMENT Filed Sept. 24, 1928 2 Sheets-Sheet 2 23 mum INVENTORS ATTORNEY Patented Apr. 29, 1930 UNITED srarss serum.- OFFICE ELIOT NILES, OF BLOOMFIELD, NEW JERSEY, AND WILLIAM H. EDWARDS, OF

BAYSIDE, NEW YORK, ASSIGNORS T AMERICAN TELEPHONE AND TELEGRAP COMPANY, A CORPORATION OF NEW YORK ELECTRICAL DELAY-CIRCUIT ARRANGEMENT Application filed September 24, 1928. Serial No. 307,833.

This invention relates to'improved arrangements for introducing a time element in the operation of electric circuits and apparatus.

An illustration of one of the uses of arrangements embod ing the principles of this invention may be ound in telephone signaling circuits. In certain types of telephone systems, such for example as those termed continuously operated station auxlllary circuits, it is the practice to provide at the'subscribers station signaling apparatus which, when started by the, operators signal, Wlll remain continuously in operation untll the subscriber answers. If the operator should signal on such a line when the subscriber was absent, such apparatus would remain operated indefinitely. This would cause an eX- in the'operation of the auxiliary signal apparatus atthe station. With the arrangements of the invention the signal may be operated for a desirable interval of time and then automatically discontinued. Sometimes the opposite efiect may be accomplished by the arrangements of the invention. For example, in certain alarm circuits utilized in central offices it is desirable to permit a certain condition to exist for a certain interval of time, but if the condition persists, to have an alarm circuit operate. The arrangements of the invention for introducing a time element in theoperation of electrical circuitsand apparatus may be utilized to accomplish this purpose. Other uses and purposes of the arrangements of the invention will appear more fully from the detailed description thereof hereinafter given.

In the arrangements of the invention a rectifier of the contact variety, such forerample as the copper oxide rectifier, is included in series in a circuit including a marginal relay and a constant'potential source of direct current. The rectifier will be so poled as to oppose the flow of the current through the marginal relay. This marginal relay will be adjusted so that it will not operate on the flow of current through the high resistance of the rectifier in its initial condition. However, under certain voltage values, copper oXide rectifiers decrease in resistance with time in a constant voltage circuit. This will permit greater current to flow. After a certain interval of time this current would be suficient to operate the marginal relay. This relay may control many other types of circuits and apparatus in whose operation it is desired to introduce a time element.

The invention may be more fully understood from the following description, together with the accompanying drawing in the Figures 1, 2, 3 and 4c of which the invention is illustrated. Fig. 1 is a circuit diagram illustrating the arrangements of the invention in its broader aspects. Figs. 2 and 3 are graphical illustrations of the principles of operation of the invention. Fig. 4 is an illustration of the arrangements of the invention as utilized in a telephone signaling circult.

In Fig. 1 is shown a circuit 1 which may be termed the control circuit. This circuit will include a substantially constant voltage source of direct current 2, a marginal relay 4 and a rectifier 5. The rectifier 5 may be of the contact variety, such as a copper oxide rectifier, and will be so poled as to oppose the flow of current from battery Qthrough the marginal relay 5. The marginal relay 5 may either serve to open or close a circuit 6, which may be termed the controlled circuit.

hen the control circuit 1 is closed and the current starts to flow through the rectifier 5, its initial resistance is quite high. This may be shown by the curve 7 of Fig. 2. For example, at point 8 of the curve shortly after the current starts to flow the resistance of the rectifier is high. After the current has been flowing the resistance will decrease until at a point such as 9 on the curve it is comparatively low. In other words, the rectifier will decrease in resistance with time in a constant voltage circuit, until a point is reached where the current is suificiently increased to operate the marginal relay.

In Fig. 3 are shown a set of curves such as 10,11, 12, 13 and 14 illustrating the reverse current-resistance characteristics of a rectifier with various values of voltage across it plotted against the duration of curent flow in minutes- It will be seen that with the ar rangements of the invention it is possible to introduce a time interval of substantial duration into the operation of electric circuits and a paratus. p H

In ig. 4 is shown a telephone subscribers station equipped with continuously operated auxiliary signaling circuits, the operation of which is controlled, however after a certain interval ottime by the arrangements oi the invention. At the subscribers station would be provided theusual'bell 16, condenser 17, receiver 18, transmitter 19 andswitchhook 20.' The sub.-

scribers line would be extended so that when ringing current comes in over the line it wouldbe transmitted from the tip conductor of the line through a condenser and the winding of an alternating current responsive relay 21, and thence back to the ring con;- ductor of the subscribers line. This would operate the alternating current relay 21 and would close thet'ollowing circuit: from battery 23, conductor 33, contact and armature of relay 21, conductor 34, winding of relay 22, conductors and Y36 to the battery 23.

' The closing of this circuit will operaterelay 22. The following'locking circuit for relay 22jwill then be closed: from battery 23, conductor 37, inner contact of relay 22, conductors 38 and 34-,windii1g of relay 22, conductors 3 5 and 36 to the battery 23. The opera- 'tionot relay 22 wil :also close the following circuit: from battery 23, conductor 37, outer armature and contact of relay 22, conductor 24, r'elay25, conductors 24 and 36 to the bat-- tery 2-3.- This will operate relay. 25, which will close the circuit 26 and operate the signal 27. Heretofore, the signal 27 would remain opera-ted until the subscriber answered and removed his receiver, from theswitchhook. Under such conditions talking current would flow through the relay 32. This would operate the relay 32 and close a shortcircuit comprising conductors 40 and 41 about the winding of relay 22, thereby releasing relay 22 and discontinuing the operation of the signal 27. As has been pointed out, however, if the station should be unattended the relay 27 would remain operated. indefinitely and cause aserious drain on the battery supply therefor. In accordance with the arrangements. of this invention, the marginal relay 30 and the contact rectifier 31 are added to the circuit arrangements of the prior art. lVhen relay 22 has operated and locked up and. the operator at the central oifice has ceased to ring, the following circuit will be closed: from battery23, conductor37, outer contact and armatureof relay 2 2,, conductor A subscribers line 15 is shown."

28, armature and contact of relay 21, coninterval of time the resistance of the rectifier I will have decreased .sufiiciently so thatv the y current through the marginal relay 30 will be sufficient to operate this relay. The operation of relay 30 will close a short-circuit comprisingconductors 42, 43 and'4'1 about the operating winding] of relay This will release relay 22, opening thecireuit through the relay 30, and stop the operation ofthe signal 27. Accordingly, withthe arrangements of this invention, even though the station equipped with continuously operated auxiliary signal apparatusshould be unat tended nevertheless after a desired interval of time the auxiliary signal will cease to operate V I Itis pointed out that even if the rectifier isso poled as not to oppose the current fiow, that a somewhat similar action'is obtained except that theresistance initially and after heating is much lower than in the case when the rectifier is poled to oppose the-current fio W.

Accordingly, while the arrangements offthe invention have been disclosed as embodied in certainv specific arrangement-s, it is unidere stood that they "are capable of usein'man'y andother widely'varied forms without de-. parting iromthe'spirit of the invention as defined by the appended claims;

l/Vhat is claimed is: y

1.. Acontrol circuit comprising a source of current, amarginal responsive device and a rectifier of the contact variety poled, to oppose the flow of current from said source through said device, and controlled apparatus operated by said device. control circuit comprising a source of current, amarginal relayand a copper oxide rectifier poled so as tooppose the flow of current from said source through said relay, and a controlled circuit operated by said relay.

3. A telephone line, subscribers apparatus connected thereto, means forextending said line, a responsive relay in, said line asex-c tendedna signaling circuit-operated bysaid responsive relay, a marginal relay and acontact rectifier poled to oppose the current fiow through said'marginal relay associatedjwith said signaling circuit, and means controlled by said marginal relay'for discontinuing the of current, a marginal responsive deviceand a rectifier of the contact variety poled to ppose the flow-of'current from said source through said responsive device, the constants of said source and said rectifier being so chosen that the circuit will operate on that portion of the reverse current resistance-time curve whereby a time element will be introduced in the operation of said responsive dev1ce. 5. An electrical circuit comprising a source of current a marginal responsive device and a rectifier of the contact variety, the constants of said source and said rectifier being so chosen that the circuit will operate on that portion of the reverse current resistancetime curve whereby a time element will be introduced in the operation of said responsive device.

In testimony whereof, We have signed our names to this specification this 22nd day of September, 1928.

ELIOT W. NILES. WILLIAM H. -EDWARDS. 

